Reconciliation of Weighted Average Shares Outstanding - Reconciliation of Basic to Diluted Shares Outstanding (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Basic (in shares)	186.4	187.6	189.3
Dilutive effect of shares issuable under stock-based compensation plans (in shares)	1.5	1.7	2.3
Diluted (in shares)	187.9	189.3	191.6
Anti-dilutive options to purchase common shares and restricted stock as well as contingently issuable restricted stock which are excluded from the table above (in shares)	0.2	0.2	0.2